Wheelchair and drive system therefor

Abstract

A wheelchair includes a chassis, a pair of side wheels for supporting and driving the chassis, at least one front wheel for cooperating with the side wheels in supporting the chassis, and a seat mounted on the chassis for supporting the body of a disabled person. A pair of individually moveable footrests support the feet of the person. A driving gear is mounted for rotation concentrically and in conjunction with each of the side wheels, and a lever is pivotally mounted for rotation concentric with but independent from each of the driving gears. A pawl is mounted on each of the levers for engagement and disengagement with the corresponding driving gear. A pivoted arm and a series of rods connect each lever and pawl with one of the footrests, such that movement of the footrest by the leg of the disabled person in one direction causes the pawl to engage the driving gear and the lever to drive the gear for propelling the wheelchair. Movement of the footrest in the opposite direction causes the pawl to disengage and the lever to return to its original position. The disclosed wheelchair may be adapted such that the legs of a paralyzed individual can propel the chair through use of electrical muscle stimulation.

What is claimed is: 
     
       1. A wheelchair comprising: a chair portion including a pair of upright frame members, a generally planar and horizontal seat and a generally planar and vertical back connected between said frame members for supporting the body of a disabled person, and an arm rest carried on each of said frame members;   a chassis for supporting said chair portion;   a pair of side wheels for supporting said chassis;   at least one front wheel smaller than said side wheels for cooperating therewith in supporting said chassis;   a pair of individually movable footrests connected to said chassis for supporting the feet of said persons; and   drive means connected to said footrests for propelling said wheelchair in response to movement of at least one of said footrests.   
     
     
       2. A wheelchair as defined in claim 1, wherein said drive means is further connected to said side wheels for propelling said wheelchair by driving movement of said side wheels. 
     
     
       3. A wheelchair as defined in claim 2, wherein each of said footrests are movable in response to extension and flexion of one of the legs of said person. 
     
     
       4. A wheelchair as defined in claim 3, wherein said drive means drives one of said side wheels in response to movement of one of said footrests caused by extension of one of the legs of said person. 
     
     
       5. A wheelchair comprising: a chair portion including a pair of upright frame members, a generally planar and horizontal seat and a generaly planar and vertical back connected between said frame members for supporting the body of a disabled person, and an arm rest carried on each of said frame members;   a chassis for supporting said chair portion;   a pair of side wheels for supporting said chassis;   at least one front wheel smaller than said side wheels for cooperating therewith in supporting said chassis;   means for generating linear motion in response to extension and flexion of at least one of the legs of said person; and   means for translating said linear motion into rotary movement for driving said wheelchair.   
     
     
       6. A wheelchair as defined in claim 5, wherein said linear motion generating means includes a pair of footrests for supporting the feet of said person, each of said footrests being individually linearally movable in response to extension and flexion of one of the legs of said person. 
     
     
       7. A wheelchair as defined in claim 6, further comprising means for supporting said footrests from said chassis, said supporting means including a pair of support plates and means slideably mounting one of said footrests to each of said plates. 
     
     
       8. A wheelchair as defined in claim 7, wherein said supporting means supports said footrests for linear motion in a first direction extending forwardly with respect to said chassis and in a second direction opposite said first direction. 
     
     
       9. A wheelchair as defined in claim 8, wherein said support plates are mounted so as to define an inclined planar suface such that movement of said footrests in said first direction is upwardly along the incline of said surface and movement of said footrests in said second direction is downwardly along said incline. 
     
     
       10. A wheelchair comprising: a chair portion including a pair of upright frame members, a generally planar and horizontal seat and a generally planar and vertical back connected between said frame members for supporting the body of a disabled person, and an arm rest carried on each of said frame members;   a chassis for supporting said chair portion;   a pair of side wheels for supporting and driving said chassis;   at least one front wheel smaller than said side wheels for cooperating therewith in supporting said chassis;   a pair of individually movable footrests connected to said chassis for supporting the feet of said person;   a pair of driving gears, one of said gears being mounted for rotation concentrically and in conjunction with each of said side wheels;   means for engaging each of said driving gears for individual driving movement of said gears in a first rotational direction, and for non-engaging individual movement along said driving gears in a second rotational direction opposite said first direction; and   means connecting said engaging means with said footrests such that individual movement of one of said footrests in a first linear direction causes said engaging means to move one of said driving gears in said first rotational direction, and movement of said footrest in a second linear direction opposite said first linear direction causes movement of said engaging means in said second, non-engaging rotational direction.   
     
     
       11. A wheelchair as defined in claim 10, wherein said engaging means includes a pair of levers, each of said levers being pivotally mounted for rotation concentric with but independent from one of said driving gears,   a pair of pawls, one of said pawls being pivotally mounted on each of said levers, and   means for pivotally moving each of said pawls for engagement with the corresponding one of said driving gears in response to movement of the one of said levers carrying the one of said pawls in said first rotational direction, and for disengagement from said gear in response to movement of said one of said levers in said second rotational direction.   
     
     
       12. A wheelchair as defined in claim 11, wherein said connecting means includes a pair of assemblies, each of said assemblies including an arm pivotally mounted to said chassis at a point along said arm remote from either end thereof,   a first rod pivotally connected between a first end of said arm and one of said footrests, and   a second rod pivotally connected between the end of said arm opposite said first end and one of said levers,   movement of said footrest in said first linear direction causing said first rod to pivot said arm in one direction, said second rod thereby moving said lever in said first rotational direction, and movement of said footrest in said second linear direction causing said first rod to pivot said arm in a direction opposite said one direction, said second rod thereby moving said lever in said second rotational direction.   
     
     
       13. A wheelchair as defined in claim 12, wherein said means for pivotally moving each of said pawls includes a third rod pivotally mounted at one end thereof to said second rod,   a linkage pivotally connected to the end of said third rod opposite said one end, said linkage being further pivotally mounted to said lever at the point of mounting of said pawl, and   a friction pad disposed between said pawl and said linkage,   said third rod, said linkage and said friction pad being operative to pivot said pawl into engagement with said driving gear in response to pivotal movement of said arm caused by movement of said footrest in said first linear direction, and to pivot said pawl out of engagement with said driving gear in response to pivotal movement of said arm caused by movement of said footrest in said second linear direction.